Simultaneous Nitrification and Denitrification of Wastewater Using a Silicone Membrane Aerated Bioreactor

by Waltz, Kirk Hjelte

Abstract (Summary)

The purpose of this thesis is to investigate the use of a single reactor to biologically treat wastewater by simultaneously oxidizing ammonia, and reducing nitrate and nitrite. The Environmental Protection Agency (EPA) places strict discharge restrictions on these compounds due to their inherent toxicity to humans, wildlife, and ecosystems. The use of a simultaneous system can assist the conventional wastewater treatment technology that requires separate systems, by creating a system that needs less time and smaller size to reach effluent requirements. To conduct this research, a bench-scale membrane aerated biofilm reactor was built using silicone tubing for aeration. Batch and continuous-flow experiments were conducted to investigate the reactor's capability to oxidize ammonia using a defined growth media and monitor nitrate production and reduction. Also, wastewater from a local reclamation facility was used to determine the reactor's ability to nitrify ammonia and denitrify nitrate concentrations within wastewater. The wastewater was taken from different locations within the reclamation facility, and combinations of primary and nitrified effluent were used to monitor ammonia and nitrate concentration changes. The batch experiments showed the greatest changes, and one batch experiment showed a 79% decrease in ammonium concentrations, and followed a first-order kinetics rate constant of -0.0284 hrs-1. The continuous-flow experiments showed much greater fluctuations in results, but one of the experiments showed an ammonia oxidation efficiency of 86%. The wastewater experiments had even greater fluctuations, and the effluent concentrations of ammonia, nitrate and nitrite showed no changes when compared to the influent.